This paper introduces quantum communication concepts to the scientists starting to work in the field of quantum optics
and quantum information. Several topics are covered: (1) single and entangled photon sources; (2) quantum key
distribution protocols; (3) current and future quantum communication networks; (4) experimental realization of singlephoton
sources: state-of-the-art. More details on single photon generation and characterization methods are provided on
the examples of the author’s results on room-temperature single-photon sources with definite linear and circular
polarizations.